Setting local directory from command line is not supported. You can set it in stored session.
Um...the stored session is not changing to the local directory set in the GUI (using version 4.1.6). The local directory automatically loads fine using the GUI, but not through scripting.
I have a saved session with the local and remote directory set. My settings are being saved in a winscp.ini file and the session information looks correct.
...in stored session...
LocalDirectory=C:\temp (in winscp.ini it's C:%5Ctemp)
...from command prompt...
winscp> open user@sessiondotcom
I needed to use lcd to change the local, so when I use the synchronize command in a script I'm using the correct directories.